Intraoperative Defibrillation Testing of Subcutaneous Implantable Cardioverter‐Defibrillator Systems—A Simple Issue?

Abstract

BackgroundThe results of the recently published randomized SIMPLE trial question the role of routine intraoperative defibrillation testing. However, testing is still recommended during implantation of the entirely subcutaneous implantable cardioverter‐defibrillator (S‐ICD) system. To address the question of whether defibrillation testing in S‐ICD systems is still necessary, we analyzed the data of a large, standard‐of‐care prospective single‐center S‐ICD registry.Methods and ResultsIn the present study, 102 consecutive patients received an S‐ICD for primary (n=50) or secondary prevention (n=52). Defibrillation testing was performed in all except 4 patients. In 74 (75%; 95% CI 0.66–0.83) of 98 patients, ventricular fibrillation was effectively terminated by the first programmed internal shock. In 24 (25%; 95% CI 0.22–0.44) of 98 patients, the first internal shock was ineffective and further internal or external shock deliveries were required. In these patients, programming to reversed shock polarity (n=14) or repositioning of the sensing lead (n=1) or the pulse generator (n=5) led to successful defibrillation. In 4 patients, a safety margin of <10 J was not attained. Nevertheless, in these 4 patients, ventricular arrhythmias were effectively terminated with an internal 80‐J shock.ConclusionsAlthough it has been shown that defibrillation testing is not necessary in transvenous ICD systems, it seems particular important for S‐ICD systems, because in nearly 25% of the cases the primary intraoperative test was not successful. In most cases, a successful defibrillation could be achieved by changing shock polarity or by optimizing the shock vector caused by the pulse generator or lead repositioning.

Predictors of Elevated Defibrillation Threshold with the Subcutaneous Implantable Cardioverter-defibrillator

“…9 Frommeyer et al looked at safety margin DFT testing at the time of implant in 102 patients and noted a 6.1% incidence of failed shocks at maximal device output that improved with generator and lead repositioning. 10 Alternate electrode positioning was tried in only one patient in our cohort with a BMI 4 40 kg/m 2 who failed to respond to maximum shocks with a left parasternal electrode. The electrode was moved to the right parasternal location during the index procedure without a change in defibrillation success.…”

Anesthesia for subcutaneous implantable cardioverter‐defibrillator implantation: Perspectives from the clinical experience of a U.S. panel of physicians

“…The total time from VF induction to device therapy, 13–15 seconds, exceeds that associated with TV‐ICD testing. Since the majority of failed defibrillation is due to poor device position (too anterior or inferior) and/or the electrode not placed on the fascia (excessive fat under the electrode), performing DT at a later date, does not allow for immediate repositioning of the pulse generator or electrode.…”

ICD – Primärprävention: Was ist neu?

“…B. eine ICD-Testung immer durchgeführt werden, da in etwa 25 % der Fälle ein intraoperativer ICD-Test nicht erfolgreich ist und eine Änderung von Schockpolarität oder Umpositionierung der Elektrode bzw. des S-ICD-Aggregats erforderlich sind [28].…”